Breast cancer treatment is currently limited by the inability to accurately define the subset of patients at high risk of recurrence or those who are Likely to respond well to a given form of adjuvant treatment. A complex array of molecular markers are now under investigation as potential indicators of prognosis or treatment response. Currently. the clinical significance of most of these factors is not well characterized, although a number have exhibited promising associations with breast cancer. As a means of enhancing the ability of Lombardi Cancer Center (LCC) scientists to carry out prognostic and predictive research on promising and novel molecules, we have established the Breast Cancer Serum Bank Core Facility (SBCF). The Breast Cancer Serum Bank (SBCF) core facility is responsible for maintaining and expanding a bank of sequential serum, plasma, and lymphocyte samples linked to a computer database with associated clinical and follow-up data. The core facility provides SPORE investigators with access to patient samples and consultation for design of molecular clinical correlation studies. The SBCF includes samples from breast cancer patients, and healthy women with a normal or high risk of breast cancer. The core facility allows molecules under investigation by SPORE researchers to be evaluated clinically as markers of early breast cancer, tumor burden, and for predicting response to specific therapies. Measuring such markers in plasma or serum as opposed to tumor tissue allows the serial measurements to be made during the course of treatment and follow-up. Serial changes in marker values from baseline can be correlated with disease progression and treatment failure. Once tests become available for determining carrier status for breast cancer predisposing mutations (e.g. BRCA1), the lymphocyte samples will be extremely valuable for studying the pathogenesis of irritable breast cancer. The SBCF was initially funded as a component of the Clinical Breast Cancer Research Core in the LCC Breast Cancer SPORE in 1992. At the time it was newly developed resource, with samples to be obtained from new and continuing LCC patients. Subsequent to the funding of the LCC SPORE, an extensive serum/plasma bank and clinical database with serial samples and long-term follow up on more than 1500 patients was acquired from the University of Wisconsin Cancer Center (UWCC) (described more fully in Section 5). Because of the large size and comprehensive nature of the UWCC serum bank, the scope of operations of the SBCF increased considerably, necessitating the establishment of the SBCF as a separate core facility. It 115 a primary goal of the SBCF to make the samples and the associated database accessible and available to other breast cancer SPORE centers.